Improved Quantitative Analysis Method for Extracting Stray Capacitance in Common-Mode Inductor Based on Finite Elements

The parasitic capacitance in common-mode (CM) inductors strongly impacts the high-frequency attenuation of a CM EMI filter. Quantitative analysis method of the stray capacitance in CM inductors is usually attractive for guiding the EMI filter design for evaluating the EMI filter performance. In this paper, an improved matrix operation method based on finite elements (FEMs) is proposed for extracting stray capacitance in CM inductors. Compared with the lumped capacitor network method and traditional matrix operation method, which only calculates stray capacitance of layer and neglects the layer-to-core capacitance, the proposed analysis method considers the layer-to-core capacitance, leading a better calculation accuracy and more suitable for high-frequency modeling of CM inductors with different number of turns.